M86.021
BillableAcute hematogenous osteomyelitis, right humerus
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M86.021 an HCC code?
Yes. M86.021 maps to Bone/Joint/Muscle Infections/Necrosis under the CMS-HCC V28 risk adjustment model (and Bone/Joint/Muscle Infections/Necrosis under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for M86.021
For M86.021 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed M86.021 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M86.021 is the ICD-10-CM diagnosis code for acute hematogenous osteomyelitis, right humerus. A serious bone infection of the right upper arm bone (humerus) caused by bacteria spreading through the bloodstream. M86.021 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering other osteopathies (m86-m90).
Under the CMS-HCC V28 risk adjustment model, M86.021 maps to Bone/Joint/Muscle Infections/Necrosis (HCC 92) with a community, non-dual, aged base RAF weight of 0.209. Under the older V24 model, M86.021 mapped to the same category but with a base RAF weight of 0.482 — V28 recalibrated weights across the entire model. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
The humerus is the bone of the upper arm; ensure this is the documented infection site. Because M86.021 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for M86.021 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •The humerus is the bone of the upper arm; ensure this is the documented infection site
- •Differentiate from shoulder infections (M86.011) which involve different anatomical structures
Clinical Significance
Acute hematogenous osteomyelitis of the right humerus represents serious bloodstream-spread infection to the major upper arm bone, requiring immediate intensive antibiotic therapy and possible surgical intervention. This location poses significant risk for functional impairment, pathological fracture, and chronic complications affecting arm function.
Documentation Requirements
- ✓Documentation of acute osteomyelitis specifically affecting right humerus
- ✓Evidence of hematogenous (bloodstream) origin of infection
- ✓Clinical findings of right upper arm pain, swelling, dysfunction
- ✓Imaging studies demonstrating right humeral bone infection
- ✓Blood cultures and bone biopsy/cultures when available
- ✓Treatment with IV antibiotics and surgical debridement if needed
- ✓Assessment for pathological fracture risk